A washer or cone or disk shape with a centrally located hole, designed to accommodate a flat or oval head screw and provide additional bearing area on the material being fastened. It may or may not have a flush flange feature.
NSN 5950-00-369-7623
NSN 5855-01-110-9564
NSN 6105-01-257-5716
NSN 5985-01-310-6373
NSN 2925-00-535-8397
NSN 6130-00-984-6252
NSN 5975-01-449-1462
NSN 6145-00-150-5049
NSN 5990-00-883-2962
NSN 5910-00-632-8260
NSN 5985-00-670-0176
NSN 6320-01-201-2776